Structural Health Monitoring (SHM), which can realize real time testing and online testing for structure, is a new
research field in test technology. To solve the bolt damage detection and position in large structures, this paper researches
on the application in SHM, by using piezoelectric sensor array to fix damage position and wavelet packet analysis to
pick-up damage eigenvalue. The wavelet packet theory is expounded and the optimal wavelet function for structural
damage detection is discussed. Using wavelet packet analysis to decompose the energies in each band of frequency in the
sensor signal, the damage eigenvalue is extracted out. The damage position method by piezoelectric sensor array is
discussed. In the end, an experiment of bolt loose damage detection and position is carried out. The results indicate that
the structural health monitoring based on piezoelectric sensor array is quite effective.